Traditionally, x-rays have been used in the medical industry to view bone, tissue and teeth. X-rays have also been used to treat cancerous and precancerous conditions by exposing a patient to x-rays using an external x-ray source. Treatment of cancer with x-rays presents many well documented side effects, many of which are due to the broad exposure of the patient to the therapeutic x-rays.
Minimally invasive endoscopic techniques have been developed and are used to treat a variety of conditions. Endoluminal procedures are procedures performed with an endoscope, a tubular device into the lumen of which may be inserted a variety of rigid or flexible tools to treat or diagnose a patient's condition.
The desire for improved minimally invasive medical devices and techniques have led to the development of miniaturized x-ray devices that may be used in the treatment or prevention of a variety of medical conditions. International Publication No. WO 98/48899 discloses a miniature x-ray unit having an anode and cathode separated by a vacuum gap positioned inside a metal housing. The anode includes a base portion and a projecting portion. The x-ray unit is insulated and connected to a coaxial cable which, in turn, is connected to the power source. An x-ray window surrounds the projecting portion of the anode and the cathode so that the x-rays can exit the unit. The x-ray unit is sized for intra-vascular insertion, and may be used, inter alia, in vascular brachytherapy of coronary arteries, particularly after balloon angioplasty.
International Publication No. WO 97/07740 discloses an x-ray catheter having a catheter shaft with an x-ray unit attached to the distal end of the catheter shaft. The x-ray unit comprises an anode and a cathode coupled to an insulator to define a vacuum chamber. The x-ray unit is coupled to a voltage source via a coaxial cable. The x-ray unit can have a diameter of less than 4 mm and a length of less than about 15 mm, and can be used in conjunction with coronary angioplasty to prevent restenosis.
U.S. Pat. No. 5,151,100 describes a catheter device and method for heating tissue, the device having a catheter shaft constructed for insertion into a patient's body, and at least one chamber mounted on the catheter shaft. The catheter shaft has at least one lumen for fluid flow through the shaft. Walls that are at least in part expandable define the chambers. Fluid flows, through the lumens, between e chambers and a fluid source outside the body. The chambers can be filled with the fluid after they have been placed within the body. A heating device heats liquid within at least one of the chambers, so that heat is transmitted from the liquid to surrounding tissue by thermal conduction through the wall of the chamber. Means are provided for selectively directing heat transmission toward a selected portion of surrounding tissue. The chambers are fillable with fluid separately from each other, so that the chambers can occupy any of a plurality of possible total volumes. By selecting the total volume of chambers, compression of the tissue can be controlled, and hence the effectiveness of transfer of heat to the tissue can be controlled. According to the method, the catheter device is used to heat tissue from within a duct in a patient's body. The chambers are inserted into the duct and filled with fluid. Liquid is heated within at least one of the chambers, and heat is selectively directed toward a selected portion of surrounding tissue.
U.S. Pat. No. 5,542,928 describes a thermal ablation catheter includes an elongate body member having a heating element disposed over a predetermined length of its distal end or within an axial lumen. The heating element is suspended away from an exterior surface of the elongate member to form a circulation region thereunder. Alternatively, the heating element is distributed over some or all of the axial lumen. Thermally conductive fluid can be introduced through the lumen in the elongate member and ifito the circulation region to effect heat transfer. The catheter is used to introduce the thermally conductive medium to a hollow body organ where the heating element raises the temperature of the medium sufficiently to induce injury to the lining of the organ. Optionally, an expandable cage in the catheter or on an associated introducer sheath may be used in combination with a thermal ablation catheter. The expandable cage helps center the heating element on the catheter within the body organ and prevents direct contact between the heating element and the wall of the organ. When disposed on the catheter, the cage can be useful to position a flow directing element attached to the flow delivery lumen of the catheter. Heat transfer and temperature uniformity can be enhanced by inducing an oscillatory flow of the heat transfer medium through the catheter while heat is being applied.
U.S. Pat. No. 5,230,349 discloses a catheter having the active electrode is partially covered by a heat conducting and electrically insulating heat-sink layer for localizing and controlling an electrical heating of tissue and cooling of the active electrode by convective blood flow. The '349 patent also describes a current equalizing coating for gradual transition of electrical properties at a boundary of a metallic active electrode and an insulating catheter tube. The current equalizing coating controls current density and the distribution of tissue heating.
U.S. Pat. No. 4,860,744 discloses a system and method are disclosed for providing precisely controlled heating (and cooling) of a small region of body tissue to effectuate the removal of tumors and deposits, such as atheromatous plaque, without causing damage to healthy surrounding tissue, e.g. arterial walls. Such precisely controlled heating is produced through thermoelectric and resistive heating, and thermoelectric control of a heated probe tip. The system includes a probe tip with N-doped and P-doped legs of semiconductor material, a catheter to which the probe tip is attached for insertion into a patient's body, and a system control mechanism. The probe may be used for reduction and/or removal of atheromatous obstruction in arteries or veins. It may also be used for destruction of diseased tissue and/or tumors in various parts of the body, such as the brain or the bladder. The probe may be configured for either tip heating or for side heating.
U.S. Pat. No. 5,591,162 describes a catheter that provides precise temperature control for treating diseased tissue. The catheter may use a variety of passive heat pipe structures alone or in combination with feedback devices. The catheter is particularly useful for treating diseased tissue that cannot be removed by surgery, such as a brain tumor.
Miniaturized x-rays are not foolproof, however, and still present difficulties, because the x-ray unit generates heat which can damage adjacent tissue.
The present invention is a heat sink to be used with, e.g., an endoscopic x-ray device, to remove heat generated at the site of treatment, minimizing damage to surrounding tissues.
The device is sized to fit within the design constraints of miniaturized systems.
Other features of the present inventions will become readily apparent from the detailed description and drawings.